#include <iostream>
#include <vector>
using namespace std;

class Solution {
public:
    int maxProfit(vector<int>& prices)
    {
        int ret = 0;
        int min = prices[0];
        for (int i = 1; i < prices.size(); i++)
        {
            if (prices[i] < min)
                min = prices[i];
            else if (prices[i] > min)
            {
                ret += prices[i] - min;
                min = prices[i];
            }
        }

        return ret;
    }
};